Dump WebRTC stream to a file

Question

I'd like to capture the audio and video from a WebRTC stream to a file or pair of files, if audio and video require their own individual files. The audio and video are not muxed together and are known to be available on a set of server udp ports:

Port   Encoding
5000 - VP8 video
5001 - RTCP (for video)
5002 - Opus audio @48kHz 2 channels
5003 - RTCP (for audio)

The SDP file / data is not available and DTLS may be used.

I would prefer to use avconv or ffmpeg to capture the stream, unless a better tool is suggested.

Edit: I've found that this as inquired will most likely not work. Until I hear otherwise, none of these tools support the initial DTLS handshake followed by the data transmission via SRTP.

Problem with WebRTC is that everything is encrypted using DTLS so without building/using a whole middle tier do decode it then you are out of luck. There isn't a way that I know of to turn DTLS off to inspect everything. — bond

Benjamin Trent Benjamin Trent · Accepted Answer · 2014-09-09T14:31:20

Gstreamer-1.0 pipeline would work just fine. I am not 100% sure on muxing the two streams back together but I believe it is possible(maybe with oggmux). I have tested something similar to this and was able to decode and play the streams on a linux device receiving the decrypted/demuxed rtp streams through a gateway(I use the Janus-Gateway).

gst-launch-1.0 rtpbin name=rtpbin udpsrc name=videoRTP port=5000 \
    caps="application/x-rtp, media=video, encoding-name=VP8-DRAFT-IETF-01, payload=100" ! \
    rtpbin.recv_rtp_sink_0 rtpbin. ! rtpvp8depay ! webmmux ! queue ! filesink location=video.webm sync=false async=false \
    udpsrc name=videoRTCP port=5001 ! rtpbin.recv_rtcp_sink_0 \
    udpsrc name=audioRTP port=5002 \
    caps="application/x-rtp, media=audio, clock-rate=48000, encoding-name=X-GST-OPUS-DRAFT-SPITTKA-00, payload=96" ! \
    rtpbin.recv_rtp_sink_0 rtpbin. ! rtpopusdepay ! oggmux ! filesink location=audio.ogg sync=false async=false \
    udpsrc name=audioRTCP port=5003

Dump WebRTC stream to a file

1 Answers